Recent content by NamaeKana

o.k. i get it now. we are propagating a to limit the forces so the block/animal launched doesn't break/die. so that's why we pull out x from kx^2=ma then plug x into Uel=Ug. the objective again it to limit. then after we get the final equation, we can pick a k and an x-compression that will work.

The question is shown below the --- or this question and answerbook is from U Physics 12E #7.71. I uploaded a JPG that can be seen at http://i43.tinypic.com/35j9jja.jpg I don't understand this problem. I see that to solve this Conservation of Energy and N2L are merged using x, and that h from...

thanks. i wouldn't have figured that out by myself in a millions years ;-). i get the logic, solve 1 & 3 for a, then take a and plug back into 1.

please view these images here's the problem http://i54.tinypic.com/23h6slh.jpg the solution http://i56.tinypic.com/2hhok79.jpg

oh ! now i see. it's checking if the block on top is sliding on the slab. not deriving it.

o.k., i typed it here, but it's cryptic with (subscripts) these four N2L equations: -f = m(s) a(s) F(ns) -F(Nb) -m(s)g = 0 f - F = m(b) a(b) F(Nb) - m(b) g are shown in the soln to resolve to f = ( m(s) F ) / ( (m(s) + m(b) ) where do i begin ?

I already understand the problem, but am having trouble with the algebra for textbook Fund of Physics Solutions, Halliday, 8e, Ch6 Prob 34. Copied here http://i56.tinypic.com/20uwhw4.jpg I've been staring at this solution to N2L for hours and can't figure out how to go from the top 4 N2L...

This Winter Quarter, I'll be taking Physics for Engineers - Mechanics. The textbook for the class has problems with numbers given and the answer has numbers as well. But the Physics Department's homework and exams have no numbers for questions nor answers. They are multi-step symbolic problems...

I passed 1st quarter Physics for Life Sciences with an A last spring. Now I plan to take the Calculus version this winter quarter. I looked at the the Physics department's example homeworks and exams and they are totally MULTI-step problems, 2, 3, 4, 5, and 6 steps, symbolic only. They appear...

Yf=Yo+Voy-.5gt^2 =1.5+0-4.9t^2 1.5/4.9=t^2 t=0.553 seconds ...

I meant = +156 + 12T - 16T^2

O.K. I got it now, thanks for your help ;-) ------------------------------------------------------- Yf= Yo + VoyT - .5gT^2 0 = 5280 - 12(427 - T) - 16T^2 = 5280 - 5124 + 12T - 16T^2 = -156 + 12T - 16T^2 the roots are -2.77, +3.51, and 3.51 is the RIGHT answer...

i manually figured out that for Sky#2 to fall 5280 ft, it takes T = 3.5 secs 5280 = 12(427 - T) + (16 * T^2) next i tried with variable T 5280 = 12(427 - T) - 16T^2) 5280 = 5124 - 12T -16T^2 = -156 -12T -16T^2 the root is -.375, and it's wrong but if i manually change it...

Next, I need to find T for Sky2 first, then I can calculate the free fall & chute-open times.

from 0-2 sec (.5 x 32 x 2^2)= 64 ft 5280 ft - 64 ft = 5216 ft 5216 ft / 12 ft/s = 435 sec so sky1 takes 435 + 2 = 437 secs to hit ground sky2 jumps 10 secs later 437 - 10 = 427 secs 5280 = 0 + ( 12 x (427 - T)) + (.5 x 32 T^2) the last quadratic didn't work. hmm...